Clinical Trial of Three 10% Carbamide Peroxide
Bleaching Products

Laura Tam, DDS, M.Sc

ABSTRACT

Background
A profusion of commercial bleaching systems exists on the market today, but there are few
clinical comparisons of these systems.

Methods
In this study, three different commercial 10% carbamide peroxide bleaching systems were
used by 24 patients in an overnight protocol for two weeks. Each patient used two of the
bleaching products simultaneously in a side-by-side comparison.

Results
The mean onset of tooth whitening was 2.4 ± 1.7 days. Tooth sensitivity was the most
frequent side effect, as 64% of the patients reported tooth sensitivity occurring after
4.8 ± 4.1 days and lasting for 5.0 ± 3.8 days. Although intrapatient differences were
recorded for the three commercial 10% carbamide peroxide bleaching systems by the
patients, there were no statistical differences in the time of onset of subjective tooth
whitening and the onset, frequency and duration of tooth sensitivity among the three
commercial bleaching systems when compared pairwise or independently (p < 0.05).

Conclusion
Selection of which bleaching product to use should be based on the concentration of the
active ingredient, the viscosity of the product and other marketing features. Further
research is needed to investigate the causes of tooth sensitivity and methods to reduce
its severity and frequency.

A profusion of commercial bleaching systems exists on the market today. Home bleaching
systems commonly utilize carbamide peroxide to deliver a more stable form of hydrogen
peroxide, the active bleaching agent. Most home bleaching systems contain 10% carbamide
peroxide, but different commercial brands claim superiority based on differences in the
carrier of the active ingredient, which could affect material delivery, material retention
in the bleaching tray (material viscosity) or patient compliance (tooth sensitivity,
material taste). Although there are a few reports that compare the different bleaching
systems by listing their material and marketing contents,5-6 clinical
comparisons of different bleaching systems are rare.

In this study, three commercial 10% carbamide peroxide bleaching systems were used by
24 patients in an overnight protocol maintained for two weeks to compare their subjective
clinical effects.

The bleaching treatment was performed on 24 volunteer adult dental students, staff
and patients who expressed an interest in bleaching their teeth. The indications,
contraindications, risks and benefits of bleaching were written into the consent form and
discussed with each subject. The bleaching treatment was performed on vital teeth with no
or minimal intact restorations, no or minimal dentin exposure, and no or minimal history
of tooth sensitivity. The fabrication of the bleaching trays, the dispensing of the
bleaching kits and the photographing the patients were personally supervised by the
author.

An irreversible hydrocolloid impression was taken of each patients upper arch to
fabricate stone study models. Reservoirs approximately 0.5 mm to 1.0 mm thick for the
bleaching agent were built into the bleaching trays by first applying a photopolymerizable
spacer material (LC Block-Out, Ultradent) onto the labial surfaces of the teeth to be
bleached. The number of teeth to be bleached depended on the patients smile line.
Generally, teeth 14 to 24 or 15 to 25 were prepared for bleaching on the study model. The
spacer was kept away (approximately 0.25 mm to 0.50 mm) from the gingival margin, the
interproximal contacts and the incisal and occlusal edges. A flexible 0.9-mm-thick ethyl
vinyl acetate bleaching tray was then vacuum formed and trimmed in a scalloped fashion to
avoid all soft tissue contact.

The proprietary bleaching systems under investigation were Nite White Excel (peppermint
cream flavour, Discus Dental), Platinum Professional Toothwhitening System (Colgate) and
Opalescence Whitening Gel (regular flavour, Ultradent). For each patient, two bleaching
systems were randomly selected and randomly designated "left" or
"right". The patient was to use one bleaching system for the left side and
another for the right side, thus using the two agents simultaneously. A preliminary trial
using disclosing agents in one of the bleaching materials showed no significant crossover
of bleaching material to the other side when the bleaching tray was fabricated as
described. Furthermore, mild crossover of two bleaching materials was not a serious
concern, because other teeth in addition to the central incisors were to be used for
comparing the bleaching effect.

Each patient received a daily log form, which clearly labelled which material was to be
used for which side. The log was also to record the patients smoking habits, the
patients coffee and tea intake, the presence or absence of restorations on the teeth
to be bleached, and the presence or absence of subjective tooth sensitivity before
bleaching. Patients were instructed how to place the bleaching agents into the bleaching
trays. Each patient was to wear the tray for approximately 14 consecutive nights (after
brushing and during sleep). Each patient was asked to record daily the duration of
bleaching and any subjective evaluations or effects of each bleaching agent. Patients were
advised that if they experienced tooth sensitivity or other side effects, they could
reduce their exposure to the agents by reducing either the duration or the frequency of
bleaching. The patients were free to discontinue the treatment at any time.

A pre-study photograph of the teeth was taken under standardized lighting conditions
using the same camera and dental operatory light, with and without a matching Vita shade
guide tab of the teeth to be bleached (Fig. 1). After the bleaching treatment, a
post-study photograph of each patient was taken (Fig. 2) and the daily logs were
collected. Data on the onset of tooth whitening (first patient record of subjective tooth
whitening) and the onset, frequency and duration of tooth sensitivity for each bleaching
agent were analyzed by ANOVA (p < 0.05). Paired t-tests were also performed to compare
the two bleaching agents used side-by-side on the same patient (p < 0.05).

The protocol for this study was approved by the University of Toronto Office of
Research Services Human Subjects Review Committee.

Time of Onset of Subjective Tooth
Whitening and Time of Onset,Frequency and Duration of Tooth Sensitivity as Reported by
Patients
After Bleaching Treatment

Product

Number of
patients

Onset of
whitening (days)

Frequency of
sensitivity (%)

Onset of
sensitivity (days)

Duration of
sensitivity (days)

Platinum

17 halves

2.6 ± 1.6

65

6.2 ± 4.8

4.4 ± 3.4

Opalescence

15 halves

2.1 ± 1.4

60

4.0 ± 3.7

6.2 ± 4.9

Nite White

16 halves

2.4 ± 2.0

62

3.9 ± 3.6

4.5 ± 3.0

Totals

24

2.4 ± 1.7

64

4.8 ± 4.1

5.0 ± 3.8

Side effects of the bleaching treatment presented minimal problems to the patients. Six
patients (25%) reported gum tingling, tenderness or mild sensitivity for one or two days.
One patient reported a scratchy throat for one day. One patient reported sleep
interruption and a sore jaw for a couple of days toward the end of treatment. Another
patient reported some bruxism as a response to wearing the tray. Three patients did not
like the consistency of one of the bleaching products compared with the other.

Intrapatient differences in whitening effect and tooth sensitivity by the two
commercial bleaching systems used by each patient were occasionally reported; however,
there was no clear trend for the intrapatient differences for the bleaching agents. No
intrapatient differences in tooth whitening were noted between the left and right halves.
There were no statistical differences in the time of onset of subjective tooth whitening
and the onset, frequency and duration of tooth sensitivity among the three commercial
bleaching systems when compared pairwise (paired t-test) or independently (ANOVA).